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What is a point count?

The point count is a field method to study avian population trends or response to treatment. Consider it among other methods to carefully match your sampling and field methods to your goals.

Standardized technique

To compare bird counts at different times (e.g. trends) or sites, you want to compare apples to apples. A point count produces these apples as a field method by fixing duration and area; the observer stands a t a fixed point and records everything they hear and see within the constraints. Standardization of method controls for other variables so that a different count reflects an actual difference in the number of birds present. We know different observers and other conditions lead to variable detection rates, however, and observer training is among the most vital elements to successful point count programs. Even so, can we control for everything but different numbers, e.g. if we compare counts with the same observer, time of day, duration, and weather conditions? No - read why under "adjusted point counts".

Adjusted point counts

Even with the same observer etc., there is not an obvious relationship between the presence of a bird at the count site and its likelihood of being detected. Many of the newer methods such as distance or double-observer techniques seek to overcome this by providing a way to estimate the number of birds missed. These methods are called adjusted point counts, because they attempt to adjust for variable detectability and provide an actual estimate of bird numbers rather than an index of abundance. If the adjusted point count actually produces good estimates of the number present rather than an index, then comparing numbers from different counts is more reasonable. The sources below will introduce you to the basic techniques and the adjusted point count methods.

Protocols: Literature on Point Count Methods

Viewing the references list below, and in turn the literature they cite, will provide the reader with a solid background in understanding protocols currently used by many point count monitoring programs. If you are still planning your study, consulting with a statistician or biometrician now on these topics will greatly increase the chance of your study design matching your objectives.

  • Thompson, W.L. 2002. Towards Reliable Bird Surveys: Accounting for Individuals Present but Not Detected. Auk 119(1):18-25.

  • Bart, J. and S. Earnst. 2002. Double Sampling to Estimate Density and Population Trends in Birds. Auk 119(1):36-45.

  • Rosenstock, S.S., D.R. Anderson, K.M. Giesen, T. Leukering, and M.F. Carter. 2002. Landbird Counting Techniques: Current Practices and an Alternative. Auk 119(1):46-53.

  • Nichols, J.D., J.E. Hines, J.R. Sauer, F.W. Fallon, J.E. Fallon, and P.E. Heglund. 2000. A Double-observer Approach for Estimating Detection Probability and Abundance from Point Counts. Auk 117(2):393-408.

  • Hamel, P.B., W.P. Smith, D.J. Twedt, J.R. Woehr, E. Morris, R.B. Hamilton, and R.J.Cooper. 1996. A land manager's guide to point counts of birds in the Southeast. Gen. Tech. Rep. SO-120. U.S. Department of Agriculture, Forest Service, Southern Research Station. 39 p. Get Adobe Acrobat version.

  • Huff, M.H., K.A. Bettinger, H.L. Ferguson, M.J. Brown, B. Altman. 2000. A Habitat-Based Point-Count Protocol for Terrestrial Birds, Emphasizing Washington and Oregon. Gen. Tech. Rep. PNW-GTR-501, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR. 39 p. Get Adobe Acrobat version.

  • Nur, N., S.L Jones, and G.R. Geupel. 1999. A Statistical guide to data analysis of avian monitoring programs. Biol. Tech. Pub. R6001-1999. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. 54 p. Get Adobe Acrobat version.

  • Ralph, C.J., G.R. Geupel, P. Pyle, T.E. Martin, D.F. DeSante. 1993. Handbook of Field Methods for Monitoring Landbirds. Gen. Tech. Rep. PSW-GTR-144. U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Albany, CA. 41 p. Get Adobe Acrobat version.

  • Ralph, C.J., J.R. Sauer, S. Droege, technical editors. 1995. Monitoring Bird Populations by Point Counts. Gen. Tech. Rep. PSW-GTR-149, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Albany, CA. 187 p. Get pdf version (HTML index to multi-part pdf document).